Concrete aggregate testing device



M. A. WECKERLY 2,043,457

CONCRETE AGGREGATE TESTING DEVICE Filed April 6, .1932

June 9; 1936.

2 Sheets-Sheet l 5 5' I Mark A. Weck /g INVENTOR.

A TTORNEY.

June 9,- 1936. M. A. WECKERLY 2,043,457

CONCRETE AGGREGATE TESTING DEVLCE Filed April 6, 1952 2 Sheets-Sheet 2I'N.VENTOR. Mark A. Weaker/y.

A TTORNE Y.

Patented June 9, 1936 I UNITED STATES CQNCRETE AGGREGATE TESTING DEVICEMark A; Weckerly,.Toledo, Ohio, assignor to Toledo Scale ManufacturingCompany, Toledo, Ohio, a corporation of New Jersey Application April 6,1932, Serial-No.- 603,579.

3 Claims;

. Concrete is made of cement, water and: sand;

gravel or crushed. stone; a mixture of sandand gravel or crushedstoneoften being used. Other inert materials, such as cinders and slag, aresometimes substituted in wholeor in partfor the sand and gravel. Thesand, gravel and other inert materials are known as aggregates.

The economical production of'concrete having maximum strengthhis.dependent upon proper proportioning of the materials entering into eachbatch, particularly the water and cement, since thestrength of theconcrete depends largely upon the. water-cement ratio. There. ispractically always some Water adhering to the particles. of sand andother fine aggregates which constitutes an. unknown variable. Such wateris. known as surface moisture, and-ait may vary in. quantity from: lessthan 1. per cent of the weight of sand which has been piled in coveredsheds for a long while to nearly 15 per cent of the weight of freshlywashedsanid or of unprotected sand after a rain. Each 1 per cent ofvari-- ation of surface moisture in the aggregate may change thewater-cement ratio 4 per cent or more. Because of such variation it has.been customary'to build concrete structures with factors of safetyranging up to 9, and large factors of safety employed to insure properstrength.re.- quire more material to be used than wouldibe necessary ifsmaller factors could be employed. The determination of the amountofwater ad-.- hering to the sand is, therefore, an important prerequisiteto the eflicient production of concrete. It has been attempteditocompensatefor surface moisture in the sandlby. so-oalledrvolumetricdisplacement or inundation methods, but many authorities on concreteconstruction have become dissatisfied with such methods and nowrecommend proportioning the concrete ingredi ents more accurately on thebasis of weight.

The principal object of my invention is the provision of improved meansfor determining with accuracy the amount of surface moisture and/ortotalmoisture in sand and other concrete aggregates;

Another object of this invention is the pro-.- vision of improved meansfor determining with accuracy characteristics of concrete. aggregates,knowledge of which is necessary for. economical production of concretehaving high strength and durability.

A further object is the provision of improved means for determining thespecific gravity'of concrete aggregate and other water insolublematerial.

A furtherobject isthe provision of improved means. for determining theamount of moisture adhering tothe surfaces of concrete aggregates andsimilar materials.

A further object is the provision of improved means of determining theamount of the' socalled water of crystallization in sand and otherconcrete aggregates.

A still further object of the invention is the provisionrof-improvedmeans for determining the totalimoisture content of sand and. otherconcrete aggregates.

These and other objects and advantages will be apparent from thefollowing description and the accompanying drawings wherein similarreference numerals designate similar parts throughout the several views.

In the-drawingsaa Figure I is a front elevational view of a scaleembodying one of the several possible different formsof my invention.

Figure II isanenlarged front elevational view of. theload-counterbalancing and" indicating mechanism thereof.

Figure III is an enlarged cross sectional view of the receptacle forthe'material to be tested for moisture.

Figure IV is a fragmentary sectional back View through-a portion of the.housing and showing, the mechanism of a manually operated pointer.

Figure V is a sectional view along the line V.V of Figure IV.

Referring to the drawings in detail, the scale with which I haveshownthe embodiment of my invention' incorporated is of the well knownToledo-type and fully illustrated and explained in UnitediStatesPatentNo. 1,543,768 to Halvor O. Hem,.and:Iwi1l, therefore, describe it onlyinsofar as islnecessary to properly disclose my invention. The scale asshowncomprisesa base I, prefer+ ably'a:solidzironcasting, which ismounted on Wheels 2 for ease in transportation. Suitableleverxmechanism: (not shown) supported by the base: I in turn' supportsaload+receiving platform 3.; Thelevermechanismpivotally engages thebottomiofra connecting rodd and serves to transmitthef'orcexofa-loadstanding on the platform to aratiolever 5.fulcrumed at 6 in acolumn 1 which. is rigidly. bolted to: an extending end of the basevl.Iii-spaced relation with the fulcrum pivot:irr'ztheleverrfv are a loadpivot 8 and a force transmission" pivot 9: The upper end of theconnecting rod: engages" a stirrup l0 suspended from the load.pivots-8.-The force transmission pivot 9 is equipped with a stirrup II and isengaged by a short connecting rod l2 whose upper end is connected to astirrup i3 engaging a load pivot 14 fixed in a ratio lever l5 fulcrumedat I6 upon the bracket I'I stationed and secured within a substantiallywatch-case-shaped housing is which surmounts the column I.

The lever l 5 is also provided with a nose pivot l9 which engages astirrup 2U fastened to the lower end of a rod 2| which is adjustablyheld .in a yoke-like member 22. Connected to this member are ribbons 23,the upper ends of which are secured to and overlie arcuate surfaces ofpower sectors 24 which are a part of the load-counterbalancing pendulums25. These pendulums also are provided with fulcrum sectors 26 havingarcuate surfaces to the lower ends of which are fastened flexiblemetallic ribbons 2? whose upper ends are secured to a frame 28 andthusform a suspension for the pendulums 25. Secured to the fulcrumsectors 26 are pendulum bodies 29 into which stems 38 are threaded andadjustably secured on the stems 30 are pendulum weights (H. A so-calledcompensating frame 32 is pivoted to the pendulums 25 at 33 and partakesof the vertical movement of the pendulum bodies. Midway between thesuspension points 33 of the frame 32 a rack 34 is pivotally suspended.The

teeth of this rack engage the teeth of a pinion (not shown) fixed on anaxle 35 mounted in suitable ball bearings in the frame 28. An indicatorhand 36 is fastened to a projecting end of the axle 35 and is thusactuated by the movements of the pendulum.

When a load is placed on the scale platform 3, the force resulting fromits weight is transmitted through the rods 4 and I2, levers 5 and l 5and the ribbons 23 to the pendulums 25 to move them outwardly andupwardly until their increased load moment balances the force. Themovement of the pendulums is proportional to the weight of a load on theplatform and the indicator being directly driven by the pendulumsassumes an angle from its initial zero position which is in proportionto the weight of the load and indicates the weight on weight indicia 31on a chart 38 which is mounted in the housing H8.

The scale thus far described is adapted to accurately indicate theweights of loads on the platform 3. For the purpose of supportingsamples of aggregates and/ or other materials to be tested, the lever 5has secured to one of its projecting ends a bracket 40 provided with apivot 4| which is in spaced relation to the fulcrum 5. This pivot 4| isengaged by a stirrup 42 and suspended therefrom is a' materialreceptacle 43 provided with a snugly fitting cover 44 having a centrallylocated vent hole 45 and a hook-like projection 46 which is driven intoits body. For the purpose of adjusting the weight of the receptacle 43,a cavity 41 is provided adapted to be filled with lead shot or otheradjusting material and closed by a screw plug 48.

The upper edge of the receptacle body is machined to form a seat for aflange on the cover 44 and the bulk of the portion of the cover whichprojects into the receptacle body is adjusted by machining so that whenthe cover is in place the capacity of the receptacle is 2 pounds ofwater. Temperature changes and matter in solution cause slightvariations in the weight of the receptacle full of water, but suchvariations as resultfrom changes in atmospheric temperature and fromimpurities ordinarily occurring in water have been demonstrated to beinconsiderable. When the receptacle is filled with water to near itsupper edge and the cover is placed thereon, some of the water is forcedthrough the vent, leaving a definite volume, and if the receptaclecontain water only, a definite weight.

When anything is placed in the receptacle 43, the force resulting fromits weight is transmitted through the levers 40 and i5 and theconnections to the pendulum load-counterbalancing mechanism. Thependulums, under the influence of the load, move outwardly and upwardlyuntil their increased weight moment balances the load in the receptacle,and the indicator hand 36 is moved to a position on the chartcorresponding to the weight of the load. The weights and proportions ofthe parts are such that a load of 2 pounds in the receptacle will causethe indicator hand to move through an angle of 90 degrees. The positionassumed by the indicator hand under the influence of the weight of a 2pound load in the receptacle may be called the 2 pound position of theindicator hand. If 2 pounds of material, such as sand, having a greaterdensity than water be placed in the receptacle and water be added tofill the receptacle to capacity, as shown in Figure III, the weight ofthe contents of the receptacle will be suflicient to move the indicatorhand beyond the 2 pound position to a point depending upon theadditional amount of water in the receptacle. The greater the density ofthe sand, and hence the higher its specific gravity, the less the bulkof a 2 pound sample and the greater the weight of the Water necessary tocomplete the filling of the receptacle; hence the greater the totalweight of the sand and water. The total weight of contents of thereceptacle may be found by solving for any value of specific gravity thefollowing equation:

where S is the weight of a specimen of sand, W is the weight of a volumeof water equal to the total capacity of the receptacle, sp. gr. is thespecific gravity of the sand, and T is the total weight of the sand andwater filling the receptacle. Since the weight of the specimen of sandhas been taken for convenience as 2 pounds and the weight of a volume ofwater equal to the total capacityof the receptacle is 2 pounds, theweight of the water which remains in the receptacle with the sand is 2pounds less the Weight of the water which is displaced, that is 2 poundsminus the quantity (1 divided by the specific gravity of the sandmultiplied by the weight of the sand.

For sand having a specific gravity of 2.50 the equation becomes:

2 2+2- )3.2 pounds The indicium indicating specific gravity of 2.50,therefore, is placed at the point on the chart to which the indicatorhand is moved by a total weight in the receptacle of 3.2 pounds. Bysimilar calculations the proper location for an indicium indicating aspecific gravity of 2.60 is determined to be the point to which theindicator hand would be moved bya total weight in the receptacle of3.23077, the indicium for specific gravity 2.67 is located at a pointcorresponding to a total weight of 3.250936 pounds, etc.

The chart beingv thus calibrated and marked with the group 53 ofspecific gravity indicia, when it is desired to determine the specificgravity of a sample of sand the sandis first surfacedried by subjectingit to moderate heat. Exposure to the sun fora short time is oftensumcient. In surface dryingthe sand care must be taken not-to drive outthe water of crystallization. Enough of the surface dry sand ispouredinto the dry receptacle 43 tocause'the indicator to move through anangle of degrees to its 2 pound position. The receptacle is then filledwith water and the cover put on, after which all water adhering to theoutside of the receptacle and cover is wiped off. The force exerted bythe weight of the contents of the receptacle acts through the lever andpendulum mechanism to cause the indicator hand to move to a position inwhich it indicates on the group of indicia 53 the specific gravity ofthe sand in the sample being tested.

In testing sand for surface moisture thesize of the sample taken dependsupon the specific gravity of the particular sand being tested formoisture. Specific gravities of most sands used as concrete aggregatesare near 2.67. For this reason, a mark on the chart at the 2 poundposition of the indicator hand is arbitrarily designated 2.67 and whensandhaving a specific gravity of 2.67 is to be tested for moisture a 2pound sample is used.

Supposing a 2 pound sample of sand having a specific gravity of 2.67 tobe placed in the receptacle and the receptacle filled with water as inmaking a test for specific gravity. If the sand were surface dry, theindicator would move to a position indicating 2.67 on the specificgravity group of indicia, since the amounts of sand and water in thereceptacle would be the same as before, and the total weight of thecontents would be 3.250936 pounds. Being the position taken by theindicator hand when there is no surface moisture in the sand, thisposition is marked 0 on the percentage of moisture group of indicia 52.If a given weight of sand which is not surface dry is placed in thereceptacle, the sand and moisture will occupy more space than would beoccupied by the same weight of surface dry sand. Therefore, less waterwill be required to fill the receptacle and the totalweight ofthecontents of the receptacle will beless than it would be if the sandwere surface dryythe more surface moisture the sand contains the lessthe weight of added water necessary to fill the receptacle, and hencethe less the total weight.

The total weight for sand having a specific gravity of 2.67 depends uponthe weight of moisture in the sand and is determined according to theequation where S is the weight of surface dry sand in the sample, X isthe weight of moisture in the sample, W is the weight of a volume ofwater equal to the total capacity of the receptacle, and T is the totalweight of the sand and water filling the receptacle.

Since the weight ofthe sample taken is 2 pounds, the quantity (S'+X)becomes 2 and the quantity S becomes 2-X. The weight of a volume ofwater equal to the total capacity of the receptacle is 2 pounds.Therefore. 2 maybe substituted in the equation forthe quantity W.Substituting these values. in the equation, we have but weight of samplemultiplied by 200 The indicia 52 on the chart representing percentagesof moisture are located by assigning val.- ues to Y ranging from 0 to25. For example, the

location of the indicium for 10 per cent of moisn ture is determinedthus:

Hence the indicium for 10 per cent of moisture is located at the pointto which the indicator hand is moved by a total load of 3.1372 pounds inthe receptacle.

If the specific gravity of the sand being tested for surface moisture isbelow 2.67, it is necessary to use a heavier sample in order that thepercentage of moisture may be indicated on the same group 52 of indicia.If the specific gravity of the sand in the sample is higher, a lightersample is used.

The indicia of the weight of sand group 5| are so located that a weightof surface dry sandin the receptacle sufficient to move the indicator tothe indicium corresponding to the specific gravity of the sand pluswater sufilcient to fill the receptacle when the cover is in place willmove the in dicator hand to the zero mark on the percentage of moisturegroup, that is, to the 3.250936 position.

The indicia in the weight of sand group 5| are located by substitutingfigures representing specific gravities, ranging from 2.50 to 2.80, forsp. gr. in the equation.

sp. gr.

where S" is the weight of the sample of surface dry sand, W" is theweight of a volume of water equal to the total capacity of thereceptacle, and sp. gr. is the specific gravity of the sand.Substituting, for example, a value of 2.60 for sp. gr. and solvingforS", We obtain 2.03277. Using the value 2.60 for sp. gr. and the value2.03277 for the quantity S+X in the equation sp.gr.

we obtain 2.03277X 4.03277 +X)T But of the moisture and is equal to2.03277 pounds minus S, that is, the weight of the sample minus thesurface dry weight of the sand. Therefore By substituting this value ofX and simplifying, the value of T becomes for a sample of sand having aspecific gravity of 2.60. This is the same value for T as was found fora 2 pound sample of sand having a specific gravity of 2.67, thusindicating that the total weight of a 2.03277 pound sample of sandhaving a specific gravity of 2.60 and containing a certain percentage ofsurface moisture, with enough water added to fill the receptacle, is thesame as the total weight of a 2 pound sample of sand having a specificgravity of 2.67 and containing the same percentage of surface moisturewith enough water added to fill the receptacle. Similarly, it can beshown that the value of T is the same for sand of any specific gravityif the weight of the sample employed is such as to move the indicatorhand to the indicium in the weight of sand group 5| corresponding to thespecific gravity of the sand. Hence the same percentage of moistureindicia may be used to indicate the percentage of moisture of sand ofany specific gravity.

It is sometimes desired to determine the deficiency of absorbed moistureor water of crystallization in aggregates or the amount of moisturewhich will be reabsorbed by aggregate which has been made bone dry bydriving out the absorbed moisture. Therefore, the percentage of moisturegroup of indicia 52 has been calibrated for a short distance on theminus side of zero. In making a test to determine the amount of moisturewhich will be absorbed by bone dry aggregate, the procedure is the sameas in determining the percentage of surface moisture except that thesample in the receptacle should be covered with water and allowed tostand until maximum absorption has taken place before water is added tofill the receptacle. The weight of the absorbed moisture will cause theindicator hand to move to correct indicating position beyond the zeromark on the percentage of moisture group of indicia.

In addition to the weight graduations and the groups of indicia markedSpecific gravity, Percentage of moisture and Weight of sand, the chart38 is provided with an arcuate row of graduations for use in makingsieve analyses of aggregates. The capacity and arrangement of the sieveanalysis row of graduations is such that 2 pounds of sand or otheraggregate in the receptacle will bring the indicator hand to the 100 percent mark. The sample then may be separated by screening into as manyparts as desired and when each of the parts so separated is placed inthe receptacle the indicator hand will overlie the mark on the arcuaterow of graduations 50 indicating the percentage of the whole that isconstituted by the part in the receptacle.

Adjacent to the weight of sand series of indicia 5| is a narrow slot 54through which a pointer 55 projects. The pointer is actuated from theexterior of the housing l8 by a thumb nut 56 and is adapted to be set inregistry with any of the graduations and numerals of the weight of sandseries of indicia. Secured to the rear of the chart 38, near the slot54, is a formed sheet metal stamping 51, and near one end of thestamping a twoarmed bracket 58 is riveted, the arms of the bracket beingprovided with apertures through which a pintle 59 extends. A U-shapedmember 60 is fulcrumed upon this pintle and is provided at the other endof the arms forming the U with apertures through which a stem 6|projects. One end of the stem is driven into the thumb nut 56 and onthat portion lying between the arms of the member 69 a roller 62 isfastened. This roller is covered by a section of a rubber tube 63 whichfrictionally engages a plate-like member 64 provided with two short pins55 which project into an arcuate slot 66 punched in the stamping 51. Thecenter of curvature of the arcuate slot 66 is coincident with the radialpoint of the several series of indicia on the chart. The pointer 55,previously referred to, is fastened to the plate 64. To insure drivingfriction of the roller 62 against the plate 64, a spring 67 continuouslyurges the roller 63 against the plate 64.

To prevent mistakes from occurring should the operator forget thespecific gravity determined, which determination will remain good solong as sand from the same source of supply is being used, the pointer55 is moved into registration with the proper indicium by turning thethumb nut 56, which in turn moves the plate 84 and the thereto attachedindicator 55 in a manner which can be readily understood by referring toFigures IV and V.

The embodiment of my invention herein shown and described is to beregarded as illustrative only, and it is to be understood that theinvention is susceptible to variation, modification and change withinthe spirit and scope of the subj oined claims.

Having described my invention, I claim:

1. In apparatus for determining characteristics of concrete aggregates,the combination of a sample receptacle of definite volume, automaticload-counterbalancing means, means for connecting said receptacle tosaid automatic loadcounterbalancing means so that the load in saidreceptacle Will be counterbalanced by said automaticload-counterbalancing means, and indicating means operatively connectedto said automatic load-counterbalancing means, said indicating meansincluding a relatively movable chart and indicator, said chart beingmarked with a series of indicia for indicating percentages of moisture,the indicia of said series being located in positions to which saidindicator will be brought by total loads in said receptacle according tothe equation where S is the weight of surface dry aggregate in thespecimen, X is the weight of moisture in the specimen, W is the weightof a volume of water equal to the total capacity of the receptacle, sp.gr. is the specific gravity of the aggregate, and T is the total weightof aggregate and water filling the receptacle, and the equation weightof sample multiplied by 100 200 where Y is moisture in terms ofpercentage of weight of surface dry aggregate.

2. In apparatus for determining characteristics of concrete aggregates,the combination of a sample receptacle of definite volume, automaticload-counterbalancing means, means for connecting said receptacle tosaidautomatic loadcounterbalancing means so that the load in saidreceptacle will be counterbalanced by said automaticload-counterbalancing means, and indicating means operatively connectedto said automatic load-counterbalancing means, said indicating meansincluding a relatively movable chart and indicator, said chart beingmarked with a series of indicia for indicating weights of samples to beused in testing for percentage of moisture, the indicia of said seriesbeing located according to the equation I! WII S s sp. gr.

Where S" is the Weight of surface dry sand in the sample, W is theweight of a volume of water equal to the total capacity of thereceptacle, and sp. gr. is the specific gravity of the aggregate.

3. In a device of the class described, in combination, means forweighing out a definite quantity of moist aggregate, said quantity beingdependent upon its specific gravity, measuring means incorporated withsaid weighing means for measuring a definite volume comprised of saidquantity of moist aggregate and water, and means connected to saidWeighing means for automatically indicating the percentage of moisturein said moist aggregate.

MARK A. WECKERLY.

